Abstract

Secondary metabolites play a crucial role in marine invertebrate chemical ecology. Thus, it is of great importance to understand factors regulating their production and sources of variability. This work aimed to study the variability of the bromotyrosine derivatives in the Mediterranean sponge Aplysina cavernicola, and also to better understand how biotic (reproductive state) and abiotic factors (seawater temperature) could partly explain this variability. Results showed that the A. cavernicola reproductive cycle has little effect on the variability of the sponges’ secondary metabolism, whereas water temperature has a significant influence on the production level of secondary metabolites. Temporal variability analysis of the sponge methanolic extracts showed that bioactivity variability was related to the presence of the minor secondary metabolite dienone, which accounted for 50 % of the bioactivity observed. Further bioassays coupled to HPLC extract fractionation confirmed that dienone was the only compound from Aplysina alkaloids to display a strong bioactivity. Both dienone production and bioactivity showed a notable increase in October 2008, after a late-summer warming episode, indicating that A. cavernicola might be able to induce chemical changes to cope with environmental stressors.

Notes

Acknowledgments

Authors thank Alan Brazo for help in the analytical HPLC analyses. Chomatrographic, spectrometric, and structural analyses were performed using facilities of the Biodiversité et Biotechnologies Marines platform at the University of Perpignan (Bio2Mar, http://bio2mar.obs-banyuls.fr/fr/index.html). The sampling was performed thanks to the diving facilities of the Station Marine d’Endoume (OSU Institut Pytheas). This work was founded partly by the Agence Nationale de la Recherche (France; ECIMAR project, ANR-06-BDIV-001-04), the European Marie Curie mobility program (MIF1-CT-2006-040065-980066, research grant n° 1.38.209.2014 awarded by Saint-Petersburg State University) and La Caixa Foundation Fellowship awarded to M.Reverter.